The present inventors are aware of prior art that provides various motor-driven or powered saws for cutting grooves into materials such as concrete pavement and the like. Indeed, this is old art. Grooves are most commonly cut in concrete pavement and related materials by such saws as a means for controlling the cracking of such materials, particularly in areas where wide seasonal temperature variations result in the concrete pavement being susceptible to cracking due to thermal expansion and contraction. In order to control this type of cracking, which cracking otherwise tends to be random and unsightly and also tends to weaken the pavement, grooves are cut in the surface of the pavement.
Concrete saws or cutters that are incorporated into some sort of vehicle that allows an operator to ride the vehicle during the cutting process are also known in the art. For example, riding concrete saws or cutters, also called “span saws” in the art, are disclosed and claimed in U.S. Pat. No. 5,724,956 issued to Ketterhagen and in U.S. Pat. No. 6,470,874 issued to Mertes. In their most basic form, such riding concrete cutters can be said to include certain common elements. For example, the riding concrete cutters of prior construction include a chassis that is movable upon a concrete surface, a cutting sub-assembly that is supported by the chassis, the cutting sub-assembly including a saw blade, a drive means for actuating the cutting sub-assembly, an operator platform that includes an operator seat, and an operator control means, such means being used by the operator to control and maneuver the chassis and the cutting sub-assembly over the concrete surface.
While such riding concrete saws are useful and beneficial for their intended purpose, these inventors have come to appreciate that there is a need to improve over this prior art in such a way that will enhance operation and improve the speed at which such concrete saws operate. For example, most prior art span saws had the sawing carriages, or cutter heads, connected together by means of a mechanical link so that the heads would move in unison. The obvious disadvantage of this arrangement is that the operator had to determine the correct head spacing and then manually attach or adjust a spacer bar for each specific sawing application. After sawing a few joints, the operator would then see if each head was sawing the same amount of concrete to insure that the blade wear was equal for each head and to maximize the sawing time. If they were not equal, then the operator would need to re-adjust the heads accordingly.
Another shortcoming in the span saws of the prior art was due to the fact that such span saws used booms that are completely mechanically attached to one another, and to the required width for the particular job at hand. If the job called for 24 foot (24′) cut and the saw had been set up previously for a 32 foot (32′) cut, then boom sections would be removed and stored away. If it was a large job that required weeks of sawing, often times the booms would be left behind when moving the span saw itself to the next job site or they would be damaged while in storage. Even if boom sections were not misplaced, the span saw may have traveled many miles down the road before completion and the booms would need to be tracked down to the location where they had been removed in the first instance. Furthermore, the boom sections tended to be matched to fit to one side or the other of the span saw, which could result in the boom sections being mixed up when they were being re-attached or re-installed for another job. Sometimes, the boom sections would be stored for a season or two, depending upon what type of slab width the contractor is required to cut, further increasing the risk that boom sections could be lost or misplaced.
Another disadvantage of the span saws of the prior art is that, in order to transport a span saw with its booms attached, a very long trailer would be required to accommodate the full width of the saw. Even with the booms attached in this fashion, they would also be vulnerable to damage since they tend to hang out very far from the main frame of the span saw.
Another disadvantage of the span saws of the prior art is that ground clearance was typically a problem, particularly when saws were transported from slab to slab. With the carriages positioned anywhere along the boom or boom sections, the entire boom needs to be elevated in order to move the span saw forwardly or rearwardly. Furthermore, extra long ramps have to be built to prevent the carriages from dragging on the ground. It is also difficult to load these units onto trailers without an extra long ramp.
The bottom line is that the span saws of the prior art, in the view of these inventors, create major problems that are related to both a lack of mobility and an inability to provide for quick set-up. As an aside, these inventors have also come to appreciate that there is a need to collect the by-products of concrete cutting during the sawing process, such by-products including potentially harmful elements that are a natural result of saw degradation and wear. That is, as the concrete saw blade is used, it also wears down, thereby distributing fine elemental contaminants at the point of cutting. These elements are best contained and prevented from being placed into the environment by capture through a slurry process. The slurry process uses a supply of water or other fluid to lubricate and cool the saw blade during cutting and to control the concrete dust that is creating during the cutting process.
In view of the foregoing, the present inventors have devised an improved riding concrete cutter that has a novel boom and carriage sub-assembly where at least two sawing blades are used to cut a single groove. This boom and carriage sub-assembly arrangement improves over prior art by replacing a forwardly-disposed boom used in riding concrete cutters of prior art with a much improved boom and saw carriage sub-assembly. A boom of this prior art type is more particularly illustrated in phantom view in U.S. Pat. No. D470,157 issued to Ketterhagen et al., which patent is drawn to a design for a concrete cutter frame and cab. As shown, the frame of that design includes a forwardly-disposed boom, the boom being disposed in a position that is transverse to the travel path of the riding concrete cutter. Use of this type of prior art concrete cutter begins as the concrete cutter is advanced to a position along a portion of a concrete slab at which a groove is to be cut. The cutter is then temporarily parked and two saws that are longitudinally-movable along the boom travel along the boom to cut a transverse groove in the concrete slab. In the prior art, it would be typical to mount the two saws in a fixed, spaced-apart relationship. The saw blades would be rotatably-actuated and positioned such that, when both saws and their saw blades are lowered, a first saw and its first saw blade are positioned just outside of the edge of the concrete slab and a second saw and its saw blade are positioned above the slab and begins to cut into it, thereby forming part of a groove at that point. The two saws are then further actuated to move longitudinally along the boom and transversely along the slab. The first saw blade cuts into the slab edge and forms another part of the groove beginning at that point. As the two saws and their respective blades continue to move along the slab, the groove that is being formed by the first saw blade eventually joins the groove that was cut by the second saw blade, the first saw blade essentially traveling behind the second saw blade but fully aligned with it. With some overlapping, a complete groove is cut. When the groove is completed, the saws can be retracted upwardly and concrete cutter advanced to the place where the next transverse groove needs to be cut, and so on.
With this configuration, it can be appreciated that there is little flexibility with the relative position of the two saws along the boom. There is also no flexibility with the relative position of the saws and the concrete surface. For example, there is little if any flexibility for the configuration of the prior art to adjust for “crowns” in the concrete that is being cut. Rather than adjusting for such crowns, one carriage and blade will tend to simply cut more deeply than the other, resulting in excessive or uneven wear of the concrete-cutting blades that are used. Further, and in order to expand the cutting width of the concrete cutter, additional boom sections must be manually attached to the existing boom. As discussed earlier, this leads to problems in proper attachment of the additional boom sections to the primary boom, misalignment of the added boom section and possible malfunctioning of the saws, and a risk of the loss or misplacement of the additional boom sections as the machine is moved between work sites and during storage in the off-season.
In the view of these inventors, there is a need to provide an improved concrete cutter having a boom and saw carriage sub-assembly that overcomes all of the foregoing disadvantages. What is needed is an improved concrete cutter having such a boom and saw carriage assembly where boom extensions are integrated with the primary boom and available for use when such is desired or required by the operator. What is also needed is such an improved concrete cutter having such a boom and saw carriage sub-assembly where saw carriage alignment and spacing is variably-adjustable along the boom. What is also needed is such an improved concrete cutter where the boom and saw carriage sub-assembly is height-variable for each saw carriage and where each saw carriage is operable independently of the other saw carriage, or carriages, used in the assembly such that the assembly automatically adjusts for contours in the profile of the concrete slab that is being cut. What is also needed is an improved concrete cutter that allows the carriage sub-assemblies to be moved towards the outer portion of a boom, whereby the boom and carriage sub-assembly can be rotated upwardly to allow for clearance of the concrete cutter during transport and movement between sites and between cuts. What is also needed is an improved concrete cutter where the boom assembly also provides a primary structural support member for the chassis of the concrete cutter. What is also needed is an improved concrete cutter having an optional vacuum system for the collection and accumulation of concrete-dust and contaminant slurry as a groove is being cut in the concrete slab.